COLLEGE STATION, Texas -- Moments after his team's first practice in pads and scrimmage on March 7, Texas A&M defensive coordinator Mark Snyder was thankful for at least one thing.

"The fortunate thing is we don't have to play tomorrow, thank goodness," he said. "We've got a ways to go."

Mark Snyder has a lot of key players to replace on the Aggie defense. Sam Khan/ESPN.com

Flashing back to his team's first practice in pads a year ago, the Aggies' second-year defensive coordinator could at least see some progress.

"We may be a little further along, but we still have a long way to go," he said.

What Snyder and the Aggies' defense accomplished last year was significant. There were numerous questions about that side of the football going into Texas A&M's 2012 season, namely depth across the board and in particular, the defensive line.

Those questions were answered throughout the year as Snyder's unit played above expectations. Damontre Moore broke out as a star at defensive end, the defensive line stayed mostly healthy and performed well in its first season in the SEC, a league known for line-of-scrimmage play. Players like Spencer Nealy and Kirby Ennis were strong on the interior line, while leadership came from linebackers Sean Porter and Jonathan Stewart.

The result was a unit that was among the best in the nation on third down (16th), one of the better scoring defenses in the country (26th) and a unit that was solid against the run (35th).

Many of those key players are gone. Moore declared for the NFL draft; Nealy, Porter and Stewart were all seniors. A unit that may have been considered the weak link a year ago -- the secondary -- might actually be a strength this fall. The charge this year for Snyder and his staff is to reconstruct the front seven.

"I think they're going to be our strength, I've got to be honest with you," Snyder said. "They've played a lot of football. They're playing with a lot of confidence right now. That group right there, I don't have to worry about them too much because they've played a lot of football. They've been in the system for a year. I see those guys communicating. I don't see that with the front seven yet because they're all so new up there."

Both starters at cornerback in 2012 -- De'Vante Harris and Deshazor Everett -- return. Harris started immediately as a true freshman and is a tremendously confident player. Everett spent time at cornerback and safety and is best known as the player who intercepted Alabama quarterback AJ McCarron to deny the Crimson Tide their final scoring opportunity and help Texas A&M secure a road upset of then nation's No. 1 team.

Everett will likely stay at corner this season as opposed to flip-flopping positions. He said he can't dwell on that one memorable play.

"For other people, it has changed [their view of me] a lot. They say they'll always remember that play," Everett said. "For me, I'm still the same. I've got to come here and work hard and keep making plays like that if I want to go somewhere."

At safety, the Aggies graduated Steven Terrell, but Howard Matthews, who started down the stretch last season, returns. The Aggies are also experimenting this spring by moving cornerback Floyd Raven to safety.

"I like Floyd at safety," Snyder said. "I hope he's liking it at safety. He just has to learn what to do. We have to play to Floyd's strengths, because Floyd can run. We just ran a little blitz [in practice] and he caught Johnny [Manziel] from the backside. That don't happen that much, but that's what he brings to the table.

"He's got speed and he's a hitter. We've just got to get him comfortable. We just have to get him taught what to do. I really think it's going to be a good move for us, but we'll see. Time will tell."

Toney Hurd Jr., who played nickel cornerback and safety last season, is emerging to help in the leadership role, Snyder said. So is Donnie Baggs, who has shifted from weakside linebacker to middle linebacker.

In the front seven, Baggs, who backed up Steven Jenkins at weakside linebacker last season, moves to the starting role at middle linebacker, Stewart's former role. A replacement for Porter must be found at strongside linebacker but so far, Butler (Kan.) Community College transfer Tommy Sanders is looking the part. Snyder said Sanders was "all over the field" in the team's first practice in pads last week.

Depth is at a premium right now on the defensive line, with injuries [Julien Obioha, Ennis] and a suspension [Ennis] keeping two returning starters out of action this spring. (It's also affecting the linebacker position, where Jenkins is sitting out with an injury.) Alonzo Williams, who played the last half of last season and started the AT&T Cotton Bowl in Obioha's place, will be a key piece this fall and the Aggies hope to find someone to replace the production Moore brought to the table when he played at an All-American level (12.5 sacks, 21 tackles for loss).

But after a solid 2012 campaign, Snyder is looking for the same thing he was looking for at this time last year.